Color case hardening finish .vs Boiling...

[usabaker]

Howdy Fellas,

So here is something I have not performed yet, dealing with color case hardening finishes and their' preservation.

I picked up a Savage Model 220A 12 Ga Shotgun at auction, actually forgot that I had put a lowball bid on it, and then got notice that I won. Anyhow, she's in need of a bit of care. As you can see from the picture it has some surface oxidation, mostly on the receiver.

So my question has to do with boiling. Most time I boil and card the oxidation when I do my preservations, but I have never done it with a firearm that has a color case hardening finish. While I figure the areas that are oxidized will lose the color, will the boil and subsequent carding remove the color case hardening finish on the sections NOT oxidized?

Thanks in advance!

Bill

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[browningautorifle]

I think you'll lose case colors wherever you card.

[ssgross]

I think you'll lose case colors wherever you card.

Jim is correct. The oxidation that creates those swirls is very delicate. Boiling would most likely greatly diminish if not remove what is left of it, carding would erase any trace it was ever there. Most new factory color-cased finishes will add a clear coat over top to protect them (e.g. uberti reproductions). If you want them to last, keep solvents away, and keep the surface protected. Oxygen will slowly degrade it and make the colors less vibrant over time.

as for restoring, the only way is to redo to he color case hardening process. There is a video on YouTube somewhere of the guys at Turnbull restoration restoring the color case hardening on some old lever guns. They pack the actions in bone black or charcoal mix, heat in an electric furncace to a specific temp for specific time, then pull out and quickly water quench. Also, it's worth noting that the colors only develop in an oxygen depleted environment. So what I described above is really the only way to do it.
I've read of someone having limited success on small parts with an improvised setup of a tin can, and a charcoal BBQ, but the colors are never as vibrant as doing it a more controlled procedure. There is another video I saw somewhere of a guy doing this improvised method to fabricate some leaf springs he needed for an old rifle. worked great for functionally to temper the parts.

[RCS]

There are still gunsmiths around restoring early cartridge firearms such as the first generation Colt single action (much in demand) that do their own case hardening. i saw the work of a gunsmith who worked in a large gunshop, he even case colored a Mauser M98 action. the Mauser looked good too, but his main work was Colt 1873 revolvers.

Some years ago I converted a South American issue Remington rolling block to 22 rim fire, did alot of custom work and found an advertisement in the old Shotgun News for color case hardening from a man in South Dakota, It cost me just under $100.00 including shipping, while not the color pattern Remington used, it looks good to me.

Shop around, you might find a gunsmith to color your shotgun

[usabaker]

Some years ago I converted a South American issue Remington rolling block to 22 rim fire, did alot of custom work and found an advertisement in the old Shotgun News for color case hardening from a man in South Dakota, It cost me just under $100.00 including shipping, while not the color pattern Remington used, it looks good to me.

She's a looker for sure!... I've been looking around and everything so far looks to be 250.00+ I have been reading a bit on the subject and it doesn't look to be too hard of a process but the heating source would be the big hurdle. I'm mulling it over, the Savage 220A is not an overly rare or valuable shotgun, I just bought it because I remember using one as a kid. Now the question is, how much do I want to invest in her, just might since I have no intention of selling her anyhow. I have to do something though to kill the surface oxidation so while I figure out her future, she's going to end up in the boil.

---------- Post added at 07:44 PM ---------- Previous post was at 07:42 PM ----------

Somewhere I have some information that indicates cyanide as a possible element

The old gunsmith books I have discussed using cyanide, I think I will keep my distance on that one LOL

---------- Post added at 07:49 PM ---------- Previous post was at 07:44 PM ----------

bone black or charcoal mix, heat in an electric furncace to a specific temp for specific time, then pull out and quickly water quench. Also, it's worth noting that the colors only develop in an oxygen depleted environmen

I been looking at the process. I have a friend that makes knives and has a forge. I've not seen it so have no clue how big it is but I gonna give him a shout. Brownell carries the supplies I would need. They even have a kit, but I would need more then this old shotgun to justify the price.

---------- Post added at 07:56 PM ---------- Previous post was at 07:49 PM ----------

I have a book on gunsmithing written in the 1930s ('Advanced Gunsmithing' by W.F. Vickery).

Yup, that's one if the books, that and Clide Bakers book

---------- Post added at 08:04 PM ---------- Previous post was at 07:56 PM ----------

But.. Y'all answered my initial question in that I will lose the case color when I boil and card. Not much of it left anyhow I suppose so no really hard loss. Thank you guys!

[Eaglelord17]

Jim is correct. The oxidation that creates those swirls is very delicate. Boiling would most likely greatly diminish if not remove what is left of it, carding would erase any trace it was ever there. Most new factory color-cased finishes will add a clear coat over top to protect them (e.g. uberti reproductions). If you want them to last, keep solvents away, and keep the surface protected. Oxygen will slowly degrade it and make the colors less vibrant over time.

as for restoring, the only way is to redo to he color case hardening process. There is a video on YouTube somewhere of the guys at Turnbull restoration restoring the color case hardening on some old lever guns. They pack the actions in bone black or charcoal mix, heat in an electric furncace to a specific temp for specific time, then pull out and quickly water quench. Also, it's worth noting that the colors only develop in an oxygen depleted environment. So what I described above is really the only way to do it.
I've read of someone having limited success on small parts with an improvised setup of a tin can, and a charcoal BBQ, but the colors are never as vibrant as doing it a more controlled procedure. There is another video I saw somewhere of a guy doing this improvised method to fabricate some leaf springs he needed for an old rifle. worked great for functionally to temper the parts.

I am not a expert by any means on colour case hardening, but I recall reading most (basically all) colour case hardening finishes on modern reproductions aren't actual case hardening resulting in that colour, rather a chemical solution they apply to the metal resulting in that pattern instead. That could also have a fair bit as to why they use clear coats as the chemical reaction is only on the very surface and likely isn't as deep as a classic case hardening procedure.

[browningautorifle]

case hardening finishes on modern reproductions aren't actual case hardening resulting in that colour, rather a chemical solution they apply to the metal resulting in that pattern instead.

That is correct. The old way was far different.

[Doco overboard]

Somewhere I have some information that indicates cyanide as a possible element that was used to produce some of the vivid colors.
When packed in bone/ carbonaceous materials then quenched in a bath of water that a had a small bubbling vent that supplied air to keep the mixture rolling or bubbling.
As far as I recall , there was also maybe a few drops of oil or something in particular that was allowed to float on top that acted as an agent and helped to produce the colors.
Otherwise ,when done incorrectly a mottled gray appearance was usually the result without a bit of experimentation involved to learn the process completely.
And then finally, that it was a method that was usually guarded among the persons doing the work.
Not to mention the use of cyanide and the hazards associated with it.

[ssgross]

When packed in bone/ carbonaceous materials

The exact contents/mix/ratio of what metal was packed in before it went into the furnace would have been proprietary. Different mixes produce different types of colors.
Basic example...notice the colors aren't as vibrant as other examples.

This one is mighty pretty...but I don't think they say what's in their mix

[Flying10uk]

The question of cyanide in case hardening products cropped up some years ago, elsewhere. It was "suggested" to me that the cyanide used in case hardening products nowadays is in a "safer form" than it use to be in the past, however, this has not been confirmed. Does anyone know if this is correct or not?

It use to be considered a, potentially, highly dangerous product because of the cyanide content.